Apparatus for supporting and rotating a workpiece

ABSTRACT

A workpiece or substrate holder is rotatably supported on a revolving frame within a film deposition or coating chamber. A pair of pins are secured to the holder, symmetrically with respect to the axis of rotation of the holder, and are received within a channel formed on one side by an arcuate guide ring, having a sector thereof formed in an arcuate trackway, the radius of the trackway being less than the radius of the guide ring. Rotation of the frame advances the pins along the guide ring, and the trackway is so configured that only the leading pin enters it. As the leading pin progresses through the trackway, the lagging pin is swung out of the channel, around the leading pin in the trackway, and back into the channel as the leading pin, to rotate the workpiece holder to allow for the deposition of a film on both sides of the workpiece.

[ 1 Dec. 11, 1973 Gillie [5 1 APPARATUS FOR SUPPORTING AND ROTATlNG AWORKPIECE [75] lnventor: Robert E. Gillie, Chicago, 111.

[73] Assignee: Western Electric Company,

incorporated, New York,'N.Y.

[22] Filed: June 2, 1972 [21] Appl. No.: 260,025

[52] U.S. Cl 118/49, 118/319, 198/33 R [51 I Int. Cl. C23c 13/08 [581Field 01 Search 214/1 Q, 1 BC, 151,

214/707; 198/33 AB, 33 R; 118/319, 320, 423, 426, 49; 193/43 R, 43 CPrimary ExaminerFrank E. Werner AttorneyW. M. Kain et a1.

[57] ABSTRACT A workpiece or substrate holder is rotatably supported onarevolving frame within a film deposition or coating chamber. A pair ofpins are secured to the holder, symmetrically with respect to the axisof rotation of the holder, and are received within a channel formed onone side by an arcuate guide ring, having a sector thereof formed in anarcuate trackway, the radius of the trackway being less than the radiusof the guide ring. Rotation of the frame advances the pins along theguide ring, and the trackway is so configured that only the leading pinenters it. As the leading pin progresses through the trackway, thelagging pin is swung out of the. channel, around the leading pin in thetrackway, and back into the channel as the leading pin, to rotate theworkpiece holder to allow for the deposition of a film on bothsides ofthe workpiece.

9 Claims, 6 Drawing Figures UNLOAD STATION PATENTEUBECH 1915 3.777703sum 1 m 2 APPARATUS FOR SUPPORTING AND ROTATING A WORKPIECE BACKGROUNDOF THE INVENTION l. Field of the Invention The present invention relatesto a workpiece supporting and rotating apparatus, and in particular toan apparatus wherein a plurality of varying radii trackways rotate aholder for supporting a substrate within a vacuum chamber tosuccessively position opposite surfaces of the substrate in registrywith a film deposition device.

2. Description of the Prior Art Generally, present apparatus forsupporting a substrate within a vacuum chamber, both sides of whichsubstrate are to be metallized by a single vacuum deposition device,consists of one of two types. The first type is a relatively simpleholder, rigidly mounted to a frame, which either immovably supports thesubstrate in registry with the deposition device or carries thesubstrate in a circular orbit past the deposition device. Use of thisfirst type of apparatus requires, after one side of the substrate hasbeen metallized, that atmosphere be introduced into the chamber todissipate the vacuum therein so that the substrate may be manuallyrotated to present the opposite, unmetallized surface of the substrateto the deposition device, and then that the atmosphere in the chamber beagain evacuated. This procedure is not only time consuming, andtherefore costly, but also increases the possibility that contaminantsmay enter the chamber and reduce the quality and reliability of themetallized coating deposited on the substrate.

The second type of substrate supporting apparatus is a rotatable holder,which allows the substrate to be brought into registry with thedeposition device, and rotated, so that both sides of the substrate maybe metallized without dissipating the vacuum in the chamber. This typeof holder, however,'is generally constructed with close tolerance gears,and chains or sprockets, all of which are troublesome in a vacuumdeposition system due to the necessary lack of lubrication, hightemperature, and buildup of evaporant material. Further- SUMMARY OF THEINVENTION In accordance with the present invention, an apparatus foradvancing and rotating a workpiece includes a holder having a pivotaxis,.for supporting the workpiece, a pivot arm mounted along the pivotaxis of the holder and having a leading and a trailing end, and a drivemechanism for rotating the holder about a center. Also included isa'first facility for guiding the leading and trailing ends of the pivotarm to confine the advance of the holder to a circular are about thecenter, and a second facility, contiguous with the first facility, forguiding the leading end to pivot the arm and holder about the pivot axisand to move the trailing end into position in advance of the leading endas the holder continues to rotate about the center.

In a preferred embodiment of the invention for turning over the holder,or carrier, having the pivot axis, a pair of follower members are spacedalong .a line passing through the pivot axis and on opposite sides ofthe pivot axis. The followers bear against a first arcuate guide railhaving a first radius of curvature, and drive facilities are provided toadvance the carrier with the followers bearing against the firstguiderail to move the carrier in an arcuate path. As the followersadvance along the first guide rail a second arucate guide rail, having aradius of curvature less than the first radius of curvature, ispositioned to engage the leading follower member and to rotate thecarrier about the pivot axis into a first aslant position.

A yieldable stop is positioned to engage the leading follower member tofurther rotate the carrier into a second aslant position, and to urgethe follower against a straight guide rail section which is contiguouswith the end of the second arcuate guide rail. Further advancing of thecarrier moves the leading follower past the yieldable stop and intoengagement with a third arcuate guide rail, contiguous with the end ofthe straight guide rail section, and having a radius of curvature lessthan the radius of curvature of the first guide rail. Engagement of theleading follower with the third guide rail further rotates the carrierinto a position that completes the turnover of the carrier.

To bring the follower members back to bear against the first guide rail,instrumentalities are included for spanning the end of the third arcuateguide rail with the beginning of the first arcuate guide rail forbringing the lagging follower to bear against the first guide rail asthe carrier is rotated into the position that completes its turnover,and for bringing the leading follower to bear against the first guiderail, behind the other follower member,.when it advances out ofengagement withthe third guide rail, so that the leading followerbecomes the lagging follower, and vice versa.

In the above preferred embodiment of the invention, the first, second,third and straight guide rails define a flat plane, and the-pivot axisof the carrier is perpendicular to the plane.

Other objects, advantages and features of the invention will be apparentupon consideration of the following detailed description when taken inconjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of theapparatus of the invention, showing the configuration of a guide and atrackway portion thereof for advancing and rotating a substrate carryingworkholder relative to a vacuum deposition device;

FIG. 2 is a side elevation view of the substrate carrying apparatus;

FIG. 3 is a sectional view, taken along the line 3-3 of FIG. l,andillustrates the manner in which a substrate holder is supported andpositioned within the guide;

FIG. 4 is a view, partially sectional, taken along the line 4-4 of FIG.3, illustrating the manner in which the holder is rotatably supported;

FIG. 5 is a sectional view, taken along the line 5-5 of FIG. 1, andshows a portion of a substrate holder being received within the trackwayportion of the guide, and

FIG. 6 is a sectional view, taken along the line 6-6 of FIG. 5,illustrating the manner in which the trackway portion of the guiderotates a substrate holder.

DETAILED DESCRIPTION The workpiece carrying apparatus of the presentinvention as shown in the drawings, for advancing and rotating aworkpiece before a workstation to permit fabricating operations, such ascoating, to be performed on opposite sides thereof, and moreparticularly for advancing and rotating a ceramic substrate before avacuum deposition device within a vacuum chamber (not shown) fordepositing a metal film on opposite sides thereof, includes a pluralityof substrate holders l1, rotatably mounted along the periphery of arevolvable, reel shaped frame 12. The holders 11 bring successiveceramic substrates 13 into registry with a plurality of vacuumdeposition devices 14 in response to rotation of the frame 12. The frame12 is rotatably mounted within the opening of a U-shaped support 17, andhas an arcuate, generally circular guide track 18, having a gap sectorwith a trackway positioned therein, associated therewith. The guidetrack 18 rotates the substrate holders 11, with respect to the frame 12,in response to rotation of the frame. This alternately posi tionsopposite sides of the substrates 13 to receive a film deposition ofmetal.

More particularly, as best shown in FIGS. 1 through 3, the frame 12 iscomprised of a circular top plate 21 and a circularbottom plate 22, thetop'and bottom plates 21 and 22 being parallel and joined at theircenters by a hollow cylindrical sleeve 23 and along their peripheralsectionsby a series of equally spaced posts 26. The posts 26 impartrigidity to the frame 12 and stabilize the spacing between theperipheries of the plates 21 and 22.

A shaft 27, extended through the sleeve 23 and centered therein by anupper bushing 28 and a lower bushing 31, is confined at each of its endswithin the legs of the U-shaped support 17. The frame 12 is securedwithin the opening of the U-shaped support by the shaft 27 and issupported for rotation therethrough by a bearing 32 positioned betweenthe bottom of the frame 12 and the lower leg of the support 17. A gear33, attached to the bottom of the shaft 27 within the lower leg of aU-shaped support 17, is driven by any suitable means (not shown) toimpart rotational movement'to the shaft 27. The rotational movement ofthe shaft 27 is transferred to the frame 12 through a locking device 36,which may be a simple nut and bolt or pin, extended through both thesleeve 23 and the shaft 27.

Rotatably positioned between each pair of adjacent posts 26 is adifferent substrate holder 1 l, the spacing between adjacent posts andthe width of the holders being such as to allow unimpeded completerotation of the holders within the frame 12. As shown in FIGS. 2 through4, each holder 11 is rectangular in shape and is formed by two verticalmembers 37 and four horizontal members 38 which define three rectangularapertures in each holder 11. A different substrate 13 is positioned inregistry with each aperture on each side of the holder 11 by anysuitable mounting mechanism, such as a set of four L-shaped tabs 42. Inthis manner, each substrate holder 11 is capable of supporting sixindividual substrates 13.

Considering one of the substrate holders 1], the following descriptionapplies equally to all of the holders. The holder 11 is rotatablymounted on the frame 12 by an integral upstanding rod 43, at its top,which passes through the top plate 21 in an upper bearing 46, and by arod 47 at its bottom, which passes through a lower bearing 48 andterminates in the bottom plate 22. The rods 43 and 47 extend along thesame axis, and with the bearings 46 and 48 act as a pivot axis torotatably secure the substrate holder 11 between the top plate 21 andthe bottom plate 22 of the frame 12.

As shown in FIG. 4, a horizontal lever or pivot arm 51 is secured,parallel to the members 38, to the upper extremity of the top rod 43,and is provided at its ends with a pair of upstanding stud shafts 52 and53 having follower rollers 54 and 55, respectively, mounted thereon. Theshafts 52 and 53 are symmetrically located with respect to the point atwhich the lever 51 is secured to the top rod 43, and therefore withrespect to the axis of rotation of the holder 11. As is evident,rotation of the horizontal lever 51, in response to movement of thefollower rollers 54 and 55, rotates the substrate holder 11 with respectto the frame 12.

As shown in FIG. 3, a stationary, essentially circular cover 56 ispositioned above the top plate 21 and is secured at its center to theend of the upper leg of the U- shaped support 17. The cover 56 has aside wall 57 which extends below the bottom plate 22 of the frame 12 andrests on the upper surface of the lower leg of the U-shaped support 17.Except for two openings, the purpose of which will be explained later,the cover 56 and its wall 57 enclose the top and the side of the frame12.

Contiguous with the lower surface of the cover 56, and also secured atits center to the upper leg of the U- shaped support 17, is anessentially circular plate 58 having an outer peripheral surface 59 anda radius less than the radius of the cover 56. Also contiguous with thelower surface of the cover 56, and secured thereto, is an arcuate,essentially circular guide ring 60 having an inner peripheral surface61. The guide ring 60 is concentric with the plate 58 and has an innerradius which is greater than the radius of the plate 58 and an outerradius which is less than the radius of the cover 56. The surfaces 59and 61, and the portion of the lower surface of the cover 56therebetween, together define the guide track 18.

The track 18 receives the follower rollers 54 and 55 within a channeldefined between the surfaces 59 and 61. Preferably, the follower rollersbear lightly against the surface 61 of the guide ring 60, so that as theframe 12 rotates and the followers advance within the channel and alongthe surface 61, the pivot axis of the holder 11, formed by the rods 43and 47, moves in an are determined by the arc of the surface 61, and theholder 11 moves in a path substantially tangent to the arc of the pivotaxis. In this manner the angular position of the substrate holder 11,and therefore of the substrates 13, with respect to the frame 12, isdetermined by the position of the followers as defined by the surface61.

As shown in FIGS. 1, 5 and 6, a generally arcuate trackway 64 spans atits ends a gap sector of approximately 60 in the guide track 18. Thearcuate trackway 64 is comprised of three contiguous sections A, B andC, each section having in common an outer arcuate guide rail 66 whichhas a radius that is smaller than the radius of the guide track 18. Thesections A and C have inner arcuate guide rails 68 and 70, respectively,which are parallel to the outer rail 66, and the section B has astraight inner guide rail 72 which is contiguous at each of its endswith a different one of the guide rails 68 or 70. The ends of the guiderail 66 do not enter the channel defined between the surfaces 59 and 60,while the ends of the guide rails 68 and 70 extend within the channel,so that the channel may be considered as being continuous from the areabetween the surfaces 59 and 61, through the area defined between theguide rail 66 and the guide rails 68, 70 and 72, and back into the areabetween the surfaces 59 and 61.

Referring to FIG. 6, with the frame 12 rotating in a clockwise directionto move the pivot axis of the holder 11 in an arcuate path, thefollowers 54 and 55 advance along the surface 61 in a clockwisedirection, and the guide rail 68 of the section A of the trackway 64engages the leading follower (which, for the purpose of example, is thefollower 54) and directs the follower into the channel defined betweenthe guide rails 66 and 68. As the pivot axis continues along its arcuatepath, the leading follower 54 advances into the section A, the laggingfollower 55 is swung past the end of the guide rail 68, and the holder11 is rotated in a counterclockwise direction about the pivot axis intoa first position aslant of the tangent of the arc defined by the path ofthe pivot axis.

Continued rotation of the frame 12 advances the follower 54 through thesection A, into the section B of the'trackway 64, and into engagementwith a yieldable deflector member 74 positioned within the section B andin the path of the follower 54, which momentarily restrains the follower54 to cause the holder 11 to further pivot about its axis in acounterclockwise direction into a second position aslant of the tangentof the are defined by the pivot axis. Continued rotation of the frame 12forces the follower 54 into engagement with the straight guide rail 72,past the yieldable member 74, and into the section C of the trackway 64.t

The section C confines the follower 54 to a path which further moves itcounterclockwise with respect to the pivot axis of the holder 11 andcauses the follower 55 to swing past the end of the arcuate guide rail70 and back into the channel of the guide track 18. Finally, thefollower 54 advances out of, the section C and back into the channel ofthe track 18, with both the followers 54 and 55 again advancing in aclockwise direction along the surface 61, and with the follower 55,which was originally the lagging follower, now being the leadingfollower, and with the follower 54, which was originally the leadingfollower, now being the lagging follower.

It is seen, therefore, that the trackway 64 receives the leadingfollower of the advancing holder 11, rotates the pivot arm 51 of theholder 11 toward and past the radius of the trackway 64, swings thelagging follower past the leading follower within the trackway 64, andreguides the followers back into the guide track 18 with the followerwhich was the lagging follower now being the leading follower, and viceversa. In this manner, em substrate holder iTis rotated through 180vfith respect to the frame 12 with each complete rotation of the frame12. A chamber 76, formed between the guide rails 68, 70 and 72 and thesurface 59 of theplate 58, permits the lagging follower to swing pastthe leading follower in the trackway 64.

The side wall 57 of the cover 56 has two apertures (not shown) formedtherein. A first aperture is formed at a position 80 where substratesare to be loaded and unloaded from a substrate holder 11. A secondaperture is formed at a position 82, opposite the deposition devices 14,so that substrates 13 carried by the substrate holders 1 1 past thedeposition devices 14 may receive a metal coating thereon. Two shields84 and 86, positioned on opposite sides of the deposition devices 14,prevent lateral travel of evaporant material provided from the devices14.

In use, with the substrate carrying apparatus located within a vacuumchamber, the frame 12 is rotated through a first complete revolution tobring sequential substrate holders 11 into registry with the position atthe load and unload station, so that three substrates may be loaded ontoa first side of each substrate holder 11 in a parallel arrangement withthe pivot axis of the holder formed by the rods 43 and 47. The frame 12is then rotated through a second complete revolution to bring a secondand opposite side of successive substrate holders 1 1 into registry withthe position 80 at the load and unload station so that three additionalsubstrates may be loaded thereon. It is to be appreciated that with eachcomplete revolutiqn gf the f r ame 12 each substrate holder is rotatedthrough with respect to the frame 12, so that upon successiverevolutions of the frame 12 alternate sides of the substrate holdersllare brought into registry with the load and unload station.

With substrates 13 loaded onto all of the substrate holders 1 1', theatmosphere within the chamber is evacuated and the frame 12 isrotated.Each rotation of the frame 12 carries the substrates on one side of theholders 11 past the deposition devices 14, the first complete rotationof the frame "12 presenting the substrates 13 on the first side of thesubstrate holders 11 to the evaporator guns 14, and the second completerotation of the frame 12, after the substrate holders 11 have beenrotated through 180, presenting the substrates 13 on the second side ofthe substrate holders 11 to the deposition devices 14. After thesubstrates on both sides of the holders 11 have beenc oated by thedeposition devices 14, the vacuum within the chamber is disrupted andthe coated substrates 13 are removed from the holders 11 at the load andunload station.

While one particular embodiment of the invention has been described indetail, it is understood that various other modifications andembodiments may be devised by one skilled in the art without departingfrom the spirit and scope of the invention-For example, if it is desiredto coat both sides of a single substrate, the substrates 13 may beloaded on only one side of each substrate holderll and carried past thedeposition devices 14. In this manner, the side of each substrate 13facing away from the substrate holders 11 will be directly coated by thedeposition devices 14 as they are brought into registry therewith, andthe side of each substrate facing the substrate holders 11 will becoated by the deposition devices 14, through the apertures in thesubstrate holders 1 1, as they are brought into registry therewith.Further, it is not necessary that the apparatus of the invention be usedin combination with a vacuum deposition chamber, but rather theapparatus may be used in any application where it is desired toalternately present opposite sides of a workpiece to a workstation.

What is claimed is:

1. In an apparatus for advancing and turning over a substantially planarworkpiece:

a rotatable holder means, for supporting the workpiece in a planeparallelto its axis of rotation;

means for advancing the holder means with its axis of rotation in an arcto move the workpiece in a path substantially tangent to the arc of theaxis;

means positioned in the path of the holder means for rotating the holdermeans about its axis to a first position aslant of the tangent of thearc;

a stop means, for momentarily arresting movement-of a portion of theholder means, to further rotate the holder means about its axis into asecond position aslant of the tangent of the arc, and for then releasingthe portion of the holder means upon continued advancement of the holdermeans, and

means for returning the released holder means into the original positionwith the workpiece turned over and advancing in a path substantiallytangent to the arc of the advancing holder means axis of rotation.

2. An apparatus as recited in claim 1, wherein the means for advancingthe holder means, with its axis of rotation in an arc, comprises:

a pivot arm, secured at its midsection to the axis of rotation of theholder means, and having a leading and a trailing end;

means for rotating the and y guide means, for guiding the leadingand'trailing ends of the pivot arm, to guide the advancing holder meanswith its axis of rotation in an arc and with the workpiece moving in apath substantially tangent to the arc of the axis of rotation.

3. ln apparatus for turning an article over,

a frame, mounted for rotation, for holding the article;

a guide ring having a gap sector;

a pivot arm having its midsection secured to the frame;

a pair of guide rollers individually mounted on the ends of the arm;

means for advancing the frame with the guide rollers within the gapsector and bearing against the inner surface of the guide ring;

a trackway spanning'the gap sector for receiving the leading guideroller and for rotating the arm and holder, and

means for engaging the leading roller to further rotate the arm andframe to move the trailing roller into position to first engage the ringwhile the leading roller is moving from the trackway.

4. Apparatus as recited in claim 3, wherein the engaging meanscomprises:

a stop, positioned within the trackway, for momentarily resistingmovement of the leading roller, to further rotate the arm and frame, andfor then releasing the roller as it continues to move through thetrackway.

5. In a turnover apparatus:

a carrier means having a pivot axis and a pair of follower membersspaced along a line passing through the pivot axis and on opposite sidesof the pivot axis;

a first arcuate guide rail having a first radius of curvature;

means for advancing the carrier means with both the follower membersbearing against the guide rail to move the carrier means in an arcuatepath;

a second arcuate guide rail, having a radius of curvature less than thefirst radius of curvature, for engaging the leading follower member asit advances holder means about a center,

along the first guide rail and for rotating the carrier means about thepivot axis into a first aslant position;

a straight guide rail section contiguous with the end of the secondarcuate guide rail;

a yieldable stop, positioned for engaging the leading follower member,to further rotate the carrier means into a second aslant position andfor urging the leading follower member against the straight guide rail,whereupon further advancing of the carrier means moves the leadingfollower member past the yieldable stop, and

a third arcuate guide rail, having a radius of curva ture less than theradius of curvature of the first guide rail and contiguous with the endof the straight guide rail section for engaging the leading followermember to further rotate the carrier means into a position thatcompletes the turnover of the carrier means.

6. In a turnover apparatus as recited in claim 5, which furthercomprises:

means for spanning the end of the third arcuate guide rail with thebeginning of the first arcuate guide rail for bringing the laggingfollower member to bear against the first guide rail as the carriermeans is rotated into the position that completes its turnover, and forbringing the leading follower member to bear against the first guiderail, behind the other follower member, when it advances out ofengagement with the third guide rail, so that the leading followermember becomes the lagging follower member, and vice versa.

7. In a turnover apparatus as recited in claim 6,

wherein:

the first, second, third and straight guide rails define a flat plane,and

the pivot axis of the carrier means if perpendicular to the plane.

8. In an apparatus for supporting and guiding a substrate along anendless loop track within a vacuum chamber to successively positionopposite surfaces of the substrate in registry with a film depositiondevice:

a rotatable substrate holder, for supporting the substrate in a planeparallel to its axis of rotation;

means for advancing the holder along the track, the holder at a pointalong the track positioning a first surface of the substrate in registrywith the film deposition device;

means positioned in the path of the holder for rotating the holder aboutits axis to a first aslant position with respect to the track;

a stop means for momentarily arresting movement of a portion of theholder, to further rotate the holder to a second aslant position withrespect to the track, and for then releasing the portion of the holderupon continued advancement of the holder, and

means for returning the released holder to a position,

with respect to the track, that is opposite to the position of theholder prior to rotation thereof, to position a second and opposite sideof the substrate in registry with the film deposition device as theholder is again advanced to the point along the track.

9. Man apparatus for advancing and rotating a workpiece:

a frame mounted for rotation about a first axis;

face;

a guideway running offset from the inner surface for engaging theleading follower to pivot the holder about the second axis to positionthe trailing follower in front of the leading follower as the followersleave the guideway and again engage the inner surface.

L- 566- PT v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONpatemNo. 3,777,703 Dated ec e 11. 1973 Inventor( Robert E. Gillie It iscertified that error appears in the above identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, lines 52-63, starting with"holder"and ending with 1 "center",should be deleted, and the following should be inserted in its place:-rotatable holder for supporting the workpiece in a plane parallel toits, axis of rotation, a drive mechanism for advancing the holder withits axis of rotation in an arc to move the workpiece in a pathsubstantially tangent to the arc of the Y axis, and a guide, positionedin the path of the holder, for rotating the holder about, its axis to afirst position aslant of the tangent of the arc, Also included is a stopmechanism, for momentarily arresting movement of a portion of the holderto further rotate the holder about its axis into a second positionaslant of the tangent of the arc, and for then releasing I the portionof the holder upon continued advancement of the holder, and a facilityfor returning the released holder into the original position with theworkpiece turned over and advancing in a path substantially tangent tothe arc of the advancing holder's axis of rotation,

I Column 4, line 58, "60'" should read --60. Column 8, line 37,

"if" should read --is-.

' Signed-and. sealed this 7th day of May 19m.v I

SEAL Atte st:

EDWARD l-I.FLETGIIER,J R. c. MARSHALL ,DANN Attesting Officer iCommissioner of Patents

1. In an apparatus for advancing and turning over a substantially planarworkpiece: a rotatable holder means, for supporting the workpiece in aplane parallel to its axis of rotation; means for advancing the holdermeans with its axis of rotation in an arc to move the workpiece in apath substantially tangent to the arc of the axis; means positioned inthe path of the holder means for rotating the holder means about itsaxis to a first position aslant of the tangent of the arc; a stop means,for momentarily arresting movement of a portion of the holder means, tofurther rotate the holder means about its axis into a second positionaslant of the tangent of the arc, and for then releasing the portion ofthe holder means upon continued advancement of the holder means, andmeans for returning the released holder means into the original positionwith the workpiece turned over and advancing in a path substantiallytangent to the arc of the advancing holder means axis of rotation.
 2. Anapparatus as recited in claim 1, wherein the means for advancing theholder means, with its axis of rotation in an arc, comprises: a pivotarm, secured at its midsection to the axis of rotation of the holdermeans, and having a leading and a trailing end; means for rotating theholder means about a center, and guide means, for guiding the leadingand trailing ends of the pivot arm, to guide the advancing holder meanswith its axis of rotation in an arc and with the workpiece moving in apath substantially tangent to the arc of the axis of rotation.
 3. Inapparatus for turning an article over, a frame, mounted for rotation,for holding the article; a guide ring having a gap sector; a pivot armhaving its midsection secured to the frame; a pair of guide rollersindividually mounted on the ends of the arm; means for advancing theframe with the guide rollers within the gap sector and bearing againstthe inner surface of the guide ring; a trackway spanning the gap sectorfor receiving the leading guide roller and for rotating the arm andholder, and means for engaging the leading roller to further rotate thearm and frame to move the trailing roller into position to first engagethe ring while the leading roller is movinG from the trackway. 4.Apparatus as recited in claim 3, wherein the engaging means comprises: astop, positioned within the trackway, for momentarily resisting movementof the leading roller, to further rotate the arm and frame, and for thenreleasing the roller as it continues to move through the trackway.
 5. Ina turnover apparatus: a carrier means having a pivot axis and a pair offollower members spaced along a line passing through the pivot axis andon opposite sides of the pivot axis; a first arcuate guide rail having afirst radius of curvature; means for advancing the carrier means withboth the follower members bearing against the guide rail to move thecarrier means in an arcuate path; a second arcuate guide rail, having aradius of curvature less than the first radius of curvature, forengaging the leading follower member as it advances along the firstguide rail and for rotating the carrier means about the pivot axis intoa first aslant position; a straight guide rail section contiguous withthe end of the second arcuate guide rail; a yieldable stop, positionedfor engaging the leading follower member, to further rotate the carriermeans into a second aslant position and for urging the leading followermember against the straight guide rail, whereupon further advancing ofthe carrier means moves the leading follower member past the yieldablestop, and a third arcuate guide rail, having a radius of curvature lessthan the radius of curvature of the first guide rail and contiguous withthe end of the straight guide rail section for engaging the leadingfollower member to further rotate the carrier means into a position thatcompletes the turnover of the carrier means.
 6. In a turnover apparatusas recited in claim 5, which further comprises: means for spanning theend of the third arcuate guide rail with the beginning of the firstarcuate guide rail for bringing the lagging follower member to bearagainst the first guide rail as the carrier means is rotated into theposition that completes its turnover, and for bringing the leadingfollower member to bear against the first guide rail, behind the otherfollower member, when it advances out of engagement with the third guiderail, so that the leading follower member becomes the lagging followermember, and vice versa.
 7. In a turnover apparatus as recited in claim6, wherein: the first, second, third and straight guide rails define aflat plane, and the pivot axis of the carrier means if perpendicular tothe plane.
 8. In an apparatus for supporting and guiding a substratealong an endless loop track within a vacuum chamber to successivelyposition opposite surfaces of the substrate in registry with a filmdeposition device: a rotatable substrate holder, for supporting thesubstrate in a plane parallel to its axis of rotation; means foradvancing the holder along the track, the holder at a point along thetrack positioning a first surface of the substrate in registry with thefilm deposition device; means positioned in the path of the holder forrotating the holder about its axis to a first aslant position withrespect to the track; a stop means for momentarily arresting movement ofa portion of the holder, to further rotate the holder to a second aslantposition with respect to the track, and for then releasing the portionof the holder upon continued advancement of the holder, and means forreturning the released holder to a position, with respect to the track,that is opposite to the position of the holder prior to rotationthereof, to position a second and opposite side of the substrate inregistry with the film deposition device as the holder is again advancedto the point along the track.
 9. In an apparatus for advancing androtating a workpiece: a frame mounted for rotation about a first axis;means for rotating the frame about the first axis; a workpiece holderpivotally mounted about a secoNd axis on the frame; a guide ring havingan inner surface centered about the first axis; a leading follower and atrailing follower secured to the workpiece holder and spaced on oppositesides of the second axis for bearing against the inner surface; aguideway running offset from the inner surface for engaging the leadingfollower to pivot the holder about the second axis to position thetrailing follower in front of the leading follower as the followersleave the guideway and again engage the inner surface.